1. Technical Field
The present invention relates to an electronic component.
2. Related Art
Techniques for mounting electronic components such as semiconductor ICs have been used for circuit substrates and liquid crystal displays that are mounted to various electronic apparatuses. For example, a liquid crystal driving IC chip to drive a liquid crystal panel is mounted to a liquid crystal display. The liquid crystal driving IC chip may often be directly mounted on a glass substrate included in a liquid crystal panel or mounted on a flexible substrate (FPC) mounted to the liquid crystal panel. The former mounting structure is called a chip on glass (COG) structure, and the latter is called a chip on FPC (COF) structure. Other than those mounting structures, a chip on board (COB) structure is also known in which IC chips are mounted on a glass epoxy board or the like.
In those mounting structures, a substrate having a terminal such as a land for being connected to a wiring pattern and an electronic component having a bump electrode for being electrically contacted are used. Refer to JP-A-2005-310815. The bump electrode disclosed in JP-A-2005-310815 has a semispherical shaped resin formed on an active surface of an electronic component as a core, and a conductive film provided on the surface of the resin. When the bump electrode is pressed to a land, the core is elastically deformed. This deformation can absorb thickness variations of the bump electrode and the land. In addition, the elastic restoring force (repelling force) of the deformation can press the conductive film on the core surface to the land. As a result, the land and the bump electrode can be adequately bonded.
It is conceivable that a core having a nearly half-cylindrical shape can enhance bonding (connecting) reliability. In general, an electronic component has external connection terminals one-dimensionally arranged in a peripheral area of its active surface. When the core having the nearly half-cylindrical shape is employed, the core is formed so as to extend in parallel with the arrangement of the external connection terminals and to have a section orthogonal to the extending direction of the core with a semicircular shape, for example. Conductive films are provided so that one of the conductive films extends from each external connection terminal in a direction orthogonal to the arrangement of the external connection terminals. The conductive films intersect the core at a plurality of places each corresponding to one of the external connection terminals. Each intersected portion can function as a contact area to the land. The shape of the contact area, when the bump electrode is pressed to the land, is a circular shape if the core has a semispherical shape whereas the shape is a rectangular shape if the core has a nearly half-cylindrical shape. Increasing the contact area between the bump electrode and the land can enhance the connecting reliability.
Employing a core having a nearly half-cylindrical shape, however, needs some improvement in order to downsize an electronic component or to make the electronic component have better electrical characteristics. In general, electrodes and electrode wiring lines of elements included in an electronic component are wired inside the electronic component and exposed on the active surface of the electronic component so as to serve as external connection terminals. The wiring lines inside the electronic component are very fine. Thus, wiring the fine wiring lines causes high wiring resistance, resulting in the electrical characteristics of the electronic component being lowered. In addition, it is necessary to secure spaces for wiring the wiring lines and for keeping the elements free from influences of an electrical field and capacitances due to wiring in use. These spaces hinder downsizing the electronic component and highly integrating the elements.